Merge branch 'enhanced_viewport_overlay' into jgrpp

Further fixes for viewport lines/marker for multiplayer clients.

# Conflicts:
#	src/lang/russian.txt

src/saveload/saveload.cpp

@@ -1531,6 +1531,8 @@ size_t SlCalcObjMemberLength(const void *object, const SaveLoad *sld)
 	return 0;
 }
 
+#ifdef OTTD_ASSERT
+
 /**
  * Check whether the variable size of the variable in the saveload configuration
  * matches with the actual variable size.
@@ -1571,9 +1573,13 @@ static bool IsVariableSizeRight(const SaveLoad *sld)
 	}
 }
 
+#endif /* OTTD_ASSERT */
+
 bool SlObjectMember(void *ptr, const SaveLoad *sld)
 {
+#ifdef OTTD_ASSERT
 	assert(IsVariableSizeRight(sld));
+#endif
 
 	VarType conv = GB(sld->conv, 0, 8);
 	switch (sld->cmd) {